Anti-static coated paperboard or similar rigid material

ABSTRACT

A multiple-ply anti-static paperboard having a layer of relatively rigid material to which at least one ply of permanently anti-static/static-dissipative material is applied. Containers, as well as dividers and pads for containers, are made of such multiple-ply board materials. The permanently anti-static/static-dissipative layer prevents a static charge from being created when articles are inserted into or removed from the containers and prevents paperboard or other dust from contacting and adversely affecting the packaged article.

This is a continuation of application Ser. No. 07/585,718, filed Sep.20, 1990 which in turn a Division of application Ser. No. 07/366,434,filed Jun. 15, 1989, now U.S. Pat. No. 5,017,260, which is in turn acontinuation-in-part of application Ser. No. 07/336,733, filed Apr. 12,1989, now U.S. Pat. No. 4,966,280, which is in turn acontinuation-in-part of application Ser. No. 07/190,044, filed May 4,1988, now abandoned.

This invention relates to relatively rigid multiple-ply anti-staticpackaging materials and, particularly, paperboard materials useful forpackaging articles adversely affected by electrostatic discharge.

BACKGROUND OF THE INVENTION

Static discharge is a naturally occurring electronic phenomenon.Triboelectric charge, often referred to as static electricity, builds upin all materials to some degree, and is eventually discharged as thecharge traverses a path toward an electrical ground. Static electricitybuildup is strongest in insulative materials.

Circuit boards contain microcircuitry which can be easily damaged byelectrostatic discharge of relatively small magnitude. Magnitudes assmall as 50 volts can permanently damage these devices. For comparativepurposes, to illustrate the extreme sensitivity of microcircuits to thisphenomenon, a visible charge from a human hand to a door knob in winterwill often exceed 10,000 volts. Thus, extreme caution must be taken inprotecting such microcircuit components from electrostatic discharge.

To provide protection from electrostatic discharge for packagedarticles, a principle of physics referred to as the Faraday cage effectis often employed. Electricity does not penetrate a conductiveenclosure. The static electric charge will go around the enclosed space,seeking the path of least electrical resistance en route to ground. Bysurrounding a static sensitive article with a conductive enclosure, thearticle is shielded from electrostatic discharge originating outside ofthe enclosure.

In my co-pending U.S. patent application Ser. No. 07/336,733, I havedisclosed a multiple-ply anti-static paperboard product for use inFaraday cage-type packaging of electrostatic charge sensitive articles,such as electrical components or electrical circuit boards. Themultiple-ply paperboard product comprises a layer of high-carbon contentpaperboard sandwiched between two layers of anti-static (now defined asstatic-dissipative) material. Such multiple-ply paperboard isparticularly useful in the manufacture of dividers, pads and walls ofcontainers for packaging articles which are required to be shielded fromexposure to static discharge.

The packaging material described in the above-identified application hasbeen found to be very beneficial in the protection of articles againstdamage by static electricity, but in many instances, that materialaffords more protection against certain types of static electricity andless protection against other types of static electricity than isrequired for specific applications. Specifically, and as one example,many applications require only protection against static electricitygenerated internally of the package either by an electrical component orarticle rubbing against a portion of the package or by one portion ofthe package rubbing against another portion of the package. Inapplications of this type, there is no need for the electricalconductivity of the center ply of this multiple-ply anti-staticmaterial.

It has therefore been an objective of this invention to provide amultiple-ply package material which may be utilized in the manufactureof a container or portion of a container and which provides effectiveprotection against damage to products or articles packaged in thecontainer resulting from static electricity to which the package may besubjected.

One attempt at protecting static electricity sensitive articles againststatic electricity is disclosed in U.S. Pat. No. 4,659,958 to McNulty.This patent discloses a bag having two plies of anti-static(polyethylene) material and an electrically conductive fabric or matembedded therebetween to provide a shield from electrostatic dischargefor a bagged article. Because the bag is lined with an anti-staticmaterial, it affords protection against electrostatic charge generatedinternally of the package, but the bag does not, by itself, provideadequate rigidity for physical protection of a microcircuit component.In order to provide physical protection, the bagged article must beplaced within another cell in a rigid container. This results inadditional material and material handling costs requiring a bagenclosure, additional labor costs associated with bagging the componentor article, and additional shipping costs due to reduced packagingdensity. Reduced packaging density is due to the fact that each cell ofa container which must hold an article within a bag, rather than justthe article itself, occupies more space than the article alone. Thus,for a container having a given volume, use of bag packaging necessitateslarger size cells, resulting in the packaging of fewer articles percontainer.

Another technique for protecting static electricity sensitive articlesagainst static electricity is disclosed in U.S. Pat. No. 4,623,594 toKeough. This patent discloses that a mixture of prepolymer andanti-static agent may be applied to a substrate, such as polypropylenefiber or paper or glass, and then cured to set the anti-static agent bycontacting the mixture with electron beam radiation. Because the mixtureis cured in situ, after application to the substrate, this technique isvery limited in its application and, to date, has only been appliedcommercially to bag materials. Consequently, for physical protection,articles protected against static electricity by material treated inaccordance with the disclosure of this patent must be enclosed within abag, and that bag, if it is to be physically protected, must be packagedin another rigid container. This again results in additional materialand material handling costs, as well as reduced packaging density.

Heretofore, anti-static materials have also been applied to a cardboardsubstrate, but that cardboard substrate-applied anti-static material,usually low-density polyethylene, has been rendered anti-static by beingdoped with a chemical anti-static additive, generally some form ofamine. Unfortunately, amines have several undesirable characteristicswhen used to impart anti-static properties to packaging materials. Firstof all, amines do not render the material to which they are addedpermanently anti-static. Rather, that anti-static coating of materialloses its anti-static property over a period of time. Otherwiseexpressed, that amine-doped material has a relatively short shelf lifebecause the amines, trapped within the plastic, evaporate or gassifywith time from the plastic or other material within which the amine istrapped such that the plastic loses its anti-static property. Secondly,the amine is very corrosive to many metals, including the metals fromwhich many microcircuits are manufactured. Consequently, the amine,gassifying from the anti-static plastic, can, and often does, corrodeand impair the electrical transmission characteristics of the componentwhich the anti-static material is intended to protect. Additionally, theamines which escape from the anti-static plastic can, and often do,attack the polycarbonate boards upon which many microcircuits areapplied. In the course of attacking the polycarbonate, the amine causesstress cracks, and ultimately failure of the board. Additionally, theamines contained in the anti-static plastic are humidity dependent,meaning that the atmosphere within which the amine-doped plastic isintended to afford protection to articles contained in a package of theamine-containing anti-static material must be used in an atmospherehaving a certain minimum humidity level. In some atmospheres, such asthose which are very dry as in dry areas of the United States,amine-containing anti-static plastic materials have no anti-staticproperty.

It has therefore been one objective of this invention to provide arelatively rigid anti-static multiple-ply packaging material whichcontains no amines and which is permanently anti-static.

SUMMARY OF THE INVENTION

The invention of this application which accomplishes this objectivecomprises a relatively rigid ply of paperboard or like material to whichat least one ply of permanently anti-static/static-dissipative plasticmaterial, which material has been previously rendered anti-static, isapplied. In the preferred embodiment, that permanentlyanti-static/static-dissipative plastic material is laminated onto thepaperboard via an intermediate ply of low-density polyethylene. Theanti-static plastic material is amine free, and, in the presentlypreferred embodiment, it comprises a low-density polyethylene film whichhas been chemically coated and subjected to high-energy electron beamradiation. One such suitable amine-free coating material is identifiedas "Staticure" manufactured by MPI Metallized Products, Inc. ofWinchester, Mass.

The preferred anti-static/static-dissipative material is a low-densitypolyethylene film which has been subjected to high-energy, electron beamradiation in the manner described in U.S. Pat. No. 4,623,594. Thisprecast anti-static plastic film, which has been previously exposed toelectron beam radiation to permanently set the anti-static material, ispreferably laminated onto both sides of an untreated conductivepaperboard by layering the precast film over the paperboard while thepaperboard is coated with a thin coating of molten polyethylene. Uponsolidification of the molten polyethylene, the precast film ispermanently laminated to the paperboard.

In forming the outer layers for all embodiments described hereinabove, acorrosion inhibitor may be added to protect the packaged article fromchemical corrosion. To provide chemical protection, the added corrosioninhibitor evaporates off of the outer ply and attaches itself to thepackaged article, thereby shielding the article from the sulfuriccompounds.

These and other objects and advantages of the invention will become moreapparent from the following detailed description of the invention inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a corrugated container, with a pluralityof packaging cells partially defined therein by transverse andlongitudinal dividers of the multiple-ply anti-static paperboard of thisinvention.

FIG. 2 is a cross-sectional view taken on lines 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view of the preferred embodiment of amultiple-ply anti-static paperboard of this invention.

FIG. 4 is a diagrammatic illustration of a method of forming thepaperboard of FIG. 3.

FIG. 5 is a cross-sectional view of an alternative embodiment of themultiple-ply anti-static paperboard of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Many of the terms used throughout this application have recently beenredefined by the American National Standard Institute in their newPackaging Material Standards for ESD Sensitive Items E1A-541, publishedin June of 1988. In these new standards, packaging materials are definedas being in the "conductive" range if they have a measurable surfaceresistivity of less than 10⁴ ohms per square. Until the standards werechanged in June, 1988, "conductive materials" were defined as thosehaving measurable surface resistivity of less than 10⁵ ohms per square.Similarly, the new standard, ANSI/E1A-541-1988, defines"Static-Dissipative materials" (formerly known as static-dissipative oranti-static materials) as those having a surface resistivity greaterthan 10⁵ ohms/square, but less than 10¹² ohms/square. And, these samestandards now define "Insulative materials" as those having surfaceresistivity equal to or greater than 10¹² ohms/square. "Anti-staticmaterials" are now defined by these new standards as those materialswhich minimize electrostatic charge when rubbed against or separatedfrom themselves or other similar materials. For purposes of thisapplication, and when used in this application, the terms "anti-static,""static-dissipative," "conductive" and "insulative" shall be used asdefined in the new definitions contained in ANSI/E1A-514-1988.

With reference first to FIG. 1, there is illustrated a container 10embodying the invention of this application. This container 10 is fittedtherein with transverse dividers or partitions 12 and longitudinaldividers or partitions 13 which define the side walls of a plurality ofcells 14. Each cell 14 is designed to hold an article 15 to be shipped.Both the transverse dividers 12 and the longitudinal dividers 13 havesome excess portion 16 which extends beyond an adjacent cell 14 and intocontact with side panels 17 of the container 10, thereby defining aplurality of voids 18 or empty spaces which remain unused. As known inthe container industry, the transverse dividers 12 have vertically,downwardly extending slits, and the longitudinal dividers 13 havecorresponding vertically, upwardly extending slits, to enableinterfitting of the dividers within the container 10 to partially definethe cells 14. Alternately, the vertical slits in the transverse divider12 may be upwardly extending and the vertical slits in the longitudinaldividers 13 may extend downwardly.

As shown in FIG. 2, a lower pad 23 resides beneath the dividers, and anupper pad 22 overlays the dividers to completely enclose the cells 14.According to the invention, the transverse dividers 12, the longitudinaldividers 13, and the top 22 and bottom 23 pads are comprised of amultiple-ply anti-static paperboard 25, which is shown in FIG. 3.

The multiple-ply anti-static paperboard 25 comprises a layer ofinsulative paperboard or fiberboard 26 which is preferably sandwichedbetween two layers of low-density, anti-static polyethylene 27, as shownin FIG. 3. The interior paperboard ply 26 is electrically insulative,having a surface resistivity equal to or greater than 10¹² ohms persquare.

The preferred insulative inner layer 26 is a relatively rigid ply ofpaperboard formed by a conventional paper making slurry process tocreate a fiberboard or paperboard sheet having a surface resistivityequal to or greater than 10¹² ohms per square. The insulative propertyof the paperboard is not critical to the practice of this invention. Itis only critical that the inner layer 26 be relatively rigid such thatit may be self-standing and provide physical protection to articlescontained in the cells of the container.

A preferred embodiment of the multiple-ply anti-static paperboard 25 isillustrated in FIG. 3. In this embodiment, precast, permanentlyanti-static/static-dissipative plastic layers 27 are laminated onto theopposite sides of the conductive paperboard 26. The preferred precast,permanently anti-static/static-dissipative plastic layers 27 are layersof low-density, polyethylene film which have been coated and subjectedto high-energy, electron-beam radiation so as to render the filmpermanently anti-static and permanently static dissipative. A completedescription of the process for manufacturing such a polyethylene filmmay be found in U.S. Pat. No. 4,623,594. This polyethylene film ischaracterized by a surface resistivity of more than 10⁵ but less than10¹² ohms per square. One preferred precast, polyethylene film havingthis permanent anti-static/static-dissipative surface resistivity ismanufactured by MPI Metallized Products, Inc. of Winchester, Mass. andis identified by that company as its "Staticure" product. This"Staticure" product is particularly advantageous for use in thisapplication because it is a permanently anti-static and staticdissipative, i.e., it does not lose its anti-static andstatic-dissipative qualities or change its surface resistivity overprolonged periods of time.

With reference to FIG. 4, there is illustrated schematically the mannerin which the paperboard product 25 of FIG. 3 is manufactured. As thereillustrated, a roll 30 of paperboard 26 is unwound at a first level 31.The paperboard 26 may be electrically conductive, high-carbon contentpaperboard, or it may alternatively be nonconductive, insulativepaperboard. At a first extruding station 32, a thin film 33 oflow-density, molten, polyethylene is extruded onto the top side of thepaperboard 26. Before the polyethylene film solidifies, a first ply ofthe precast permanently anti-static/static-dissipative plastic film 27is unwound from a roll 34 and applied over the top surface of the moltenpolyethylene film 33. Rollers 34 then direct the paperboard 26, havingone ply of precast anti-static plastic film 27 applied thereto, to asecond level 35. As the paperboard 26 moves along the second level 35,the paperboard 26 passes beneath a second extruding station 56 at whicha second thin film 33 of molten, low-density polyethylene is applied tothe now top surface (formerly the undersurface) of the paperboard 26.While this second film 33 of molten polyethylene is still in the moltenstate, a second ply 27 of precast permanentlyanti-static/static-dissipative plastic film is unrolled from a roll 37onto the top surface of the molten polyethylene film 33. When thepolyethylene films 33 are solidified, they permanently secure the topand bottom plies or laminates 27 to the paperboard 26 which is nowsandwiched therebetween. The multiple-ply, anti-static paperboard 25 isnow ready to be cut for use.

Thus, according to one preferred embodiment of the invention, a layer ofpaperboard 26 or other relatively rigid ply of material is sandwiched bylayers of permanently anti-static/static-dissipative material. Theanti-static layer adjacent the article prevents sloughing or abrading ofthe electrically conductive paperboard material onto articles packagedin the material, which could cause circuit damage. It also preventsgeneration of static electricity resulting from relative movement of theprotected articles and the packaging paperboard.

The multiple-ply anti-static/static-dissipative paperboard also providessufficient rigidity to physically protect packaged articles. Thisphysical protection is achieved with a savings in material and labor, ascompared to packaging requiring a bag.

The multiple-ply anti-static/static-dissipative paperboard of thisinvention has the advantage of being permanently anti-static and ofpermanently maintaining its static-dissipative quality. Otherwiseexpressed, the invention of this application, because of thispermanence, has no shelf life. Heretofore, all anti-static and/orstatic-dissipative coatings or materials have been produced by dopingpolypropylene or other plastic materials with an amine so as to impartthe anti-static property to the polypropylene plastic. That amine,though, was solely dissipated or gassified from the polypropyleneplastic over a period of time with the result that the polypropyleneplastic lost its anti-static property over a period of time.Consequently, such material had a limited shelf life.

Because the multiple-ply anti-static/static-dissipative paperboard ofthis invention is amine free, the material does not cause aminecorrosion of metal packaged within such amine-free material.Additionally, many printed electrical circuits are imprinted onpolycarbonate plastic, which plastic is subject to stress cracking whensubjected or exposed to amines. The invention of this application,because it contains no amines, does not have this adverse effect uponpolycarbonate boards. Anti-static plastics which contain amines are alsohumidity sensitive, i.e., they are only operative and only maintaintheir anti-static properties so long as there is some minimal humiditylevel maintained in the atmosphere. The amine-containing anti-staticplastics therefore are not operative in very dry atmospheres to whichsuch anti-static materials are often exposed. The invention of thisapplication is not humidity dependent.

The multiple-ply anti-static paperboard of this invention may be made toprovide chemical protection for packaged articles. For example, acorrosion inhibitor commonly referred to as Cobra Tech, manufactured byPMC Specialty and formerly made by Sherwin Williams, may be mixed intothe outer layers 27 prior to application of these outer layers to theinterior layer 26 in order to protect copper or copper alloyed articles.This substance dissipates off the outer layer to attach itself to thecopper or copper alloy, thereby shielding the article from sulfuriccompounds in the paper. Similarly, other corrosion inhibitors could beused with other types of articles, depending upon the metal that isrequired to be protected. Because the low-densityanti-static/static-dissipative polyethylene layers of the preferredembodiment are chemically inert, they will physically shield thepackaged article from chemical corrosion. Thus, the addition of acorrosion inhibitor for this embodiment would not be necessary, butwould provide added protection against chemical corrosion.

While I have heretofore described one preferred embodiment of themultiple-ply anti-static/static-dissipative material of this inventionas embodying a single ply of paperboard or other relatively rigidmaterial sandwiched between two plies of anti-static/static-dissipativematerial, the invention of this application contemplates that suchmultiple-ply material may comprise only a single ply or coating 27 onone side of the base material 26 as illustrated in FIG. 5. Such amultiple-ply product is particularly useful in many packagingapplications wherein only a single side of the material may be exposedto electrical components or static-sensitive articles. One suchapplication for single-side coated, multiple-plyanti-static/static-dissipative material is in the production ofcorrugated paperboard material used in the manufacture of boxes orcontainers within which static-sensitive electrical components orarticles may be packaged. When used to produce permanentlyanti-static/static-dissipative corrugated paperboard, the base ply ofpaperboard is first laminated or coated with a single ply ofanti-static/static-dissipative material, and then that coated orlaminated material is subjected to a corrugating process in which it isconverted into corrugated paperboard.

As yet another alternative to the practice of this invention, the baseply of material 26, rather than being electrically insulativepaperboard, may be a relatively rigid sheet of extruded plastic materialto which the coating or ply of anti-static/static-dissipative materialmay be applied.

In the description of this invention, the preferred practice of thisinvention has been described as having the exterior ply ofanti-static/static-dissipative material laminated to the base ply ofpaperboard or other material. It is contemplated, though, that thatexterior ply may be applied to the base ply 26 by extrusion of thepermanently anti-static/static-dissipative material onto the base ply.

The preferred embodiment of the invention described hereinabove employs"Staticure," a polyethylene material which has been chemically coatedand subjected to high energy electron beam radiation as theanti-static/static-dissipative material in the multiple-ply product. Theprocess by which such "Staticure" material is created is completelydescribed in U.S. Pat. No. 4,623,594 issued Nov. 18, 1986 to MPIMetallized Products, Inc. This material has been found to be verysatisfactory in the practice of this invention. It is contemplated,though, that such polyethylene material prior to being treated so as torender it anti-static/static-dissipative may have compounded thereinconventional materials to render the polyethylene material biodegradableeither by chemical breakdown of the material or by ultraviolet lightbreakdown.

It is also contemplated, and within the scope of this invention, that inlieu of polyethylene film material being utilized in the practice ofthis invention as the permanently anti-static/static-dissipativematerial, polyethylene foam may be treated and used as the permanentlyanti-static/static-dissipative ply of material. The polyethylene foamwould otherwise be treated the same as the film in order to impart tothe foam the permanent anti-static/static-dissipative quality. Afterformation of the foam and anti-static agent and treatment by exposure toelectron beam radiation to render the foam permanentlyanti-static/static-dissipative, the foam would be adhered to thepaperboard or other relatively rigid substrate in exactly the samemanner that the polyethylene film is described hereinabove as beinglaminated to the paperboard or other substrate. The advantage of thefoam-coated product is, of course, that it provides additional physicalprotection of any products packaged with the multiple-ply foam-coatedproduct.

While I have described only a limited number of embodiments of themultiple-ply anti-static paperboard of this invention, it is to beunderstood that the invention is not to be limited solely to theseembodiments. Various other alternative embodiments will be readilyapparent to persons skilled in this art. Accordingly, it is to beunderstood that changes may be made without departing from the scope ofthe invention as particularly set forth and described.

I claim:
 1. A container for packaging an article which can be damaged bystatic electricity, comprising:a box having sidewalls and top and bottomwalls; a plurality of relatively rigid dividers located in said box,each said divider comprising a layer of relatively rigid materialsandwiched between two layers of amine-free, permanentlyanti-static/static-dissipative material, said two layers of anti-staticmaterial having a permanent surface resistivity of greater than 10⁵ butless than 10¹² ohm per square; each of said two layers being adheredwhile in a solid state to said layer of relatively rigid material andprior to being adhered to said layer of relatively rigid material beingcharacterized by the same solid amine-free, permanentlyanti-static/static-dissipative characteristics as characterize said twolayers after being adhered to said relatively rigid layer; and whereinsaid dividers partially define a predetermined number of cells withinsaid box, each said cell providing protection from electrostatic chargefor static electricity sensitive articles to be packaged therein.
 2. Acontainer as in claim 1 and further comprising:a relatively rigid toppad located between said top wall of said box and said dividers; arelatively rigid bottom pad located between said bottom wall of said boxand said dividers; wherein each said pad comprises a layer of relativelyrigid material sandwiched between two layers of permanentlyanti-static/static-dissipative material; each of said two layers beingadhered while in a solid state to said layer of relatively rigidmaterial and prior to being adhered to said layer of relatively rigidmaterial being characterized by the same solid amine-free, permanentlyanti-static/static-dissipative characteristics as characterize said twolayers after being adhered to said relatively rigid layer; and said padsand said dividers completely surrounding said cells with a layer ofpermanently anti-static/static-dissipative material.
 3. A container asin claim 1 or claim 2 wherein said anti-static/static-dissipativematerial comprises:an anti-static plastic material.
 4. A container as inclaim 1 or claim 2 wherein said permanentlyanti-static/static-dissipative material comprises low-densitypolyethylene.
 5. A container as in claim 1 or claim 2 wherein saidpermanently anti-static/static-dissipative material comprises a plasticwhich has been subjected to electron-beam radiation to impart saidsurface resistivity of more than 10⁵ but less than 10¹² ohms per square.6. A container for user in packaging an article which can be damaged bystatic electricity, comprising:a box having sidewalls and top and bottomwalls; a plurality of relatively rigid dividers located in said box,each said divider comprising a layer of paperboard sandwiched betweentwo layers of amine-free, permanently anti-static/static-dissipativematerial, said two layers of anti-static/static-dissipative materialhaving a surface resistivity of more than 10⁵ but less than 10¹² ohmsper square; each of said two layers being adhered while in a solid stateto said layer of paperboard and prior to being adhered to said layer ofpaperboard being characterized by the same solid amine-free, permanentlyanti-static/static-dissipative characteristics as characterize said twolayers after being adhered to said layer of paperboard; and wherein saiddividers partially define a predetermined number of cells within saidbox, each said cell providing protection from electrostatic charge for astatic electricity sensitive article to be packaged therein.
 7. Amultiple-ply packaging material comprising:a first layer of relativelyrigid material having first and second surfaces; a second layer ofpermanently anti-static/static-dissipative material applied to one ofsaid first and second surfaces, said second layer being amine-free andhaving been applied while in the solid state and rendered permanentlyanti-static/static-dissipative prior to application to said one of saidfirst and second surfaces; and said second layer having a surfaceresistivity of more than 10⁵ but less than 10¹² ohms per square.
 8. Amultiple-ply material as in claim 7 wherein said first layer comprises:alayer of paperboard.
 9. A multiple-ply material as in claim 7 or claim 8wherein said second layer comprises:a precast layer ofanti-static/static-dissipative plastic material laminated onto saidfirst layer.
 10. A multiple-ply material as in claim 7 or claim 8wherein said permanently anti-static/static-dissipative materialcomprises:a plastic foam material.
 11. A multiple-ply material as inclaim 7 or claim 8 wherein said second layer comprises:a plasticmaterial which has been subjected to high-energy, electron-beamradiation.
 12. A multiple-ply paperboard comprising:a first layer ofpermanently anti-static/static-dissipative material; a second layer ofpermanently anti-static material; a third layer of paperboard havingfirst and second sides, said first and second layers being permanentlyapplied to said first and second sides, respectively, of said paperboardso as to sandwich said paperboard between said first and second layers,said first and second layers being amine free and having been precastinto solid form and rendered permanently anti-static/static-dissipativeprior to application to said first and second sides of said paperboard;and wherein said first and second layers have a surface resistivity ofmore than 10⁵ but less than 10¹² ohms per square.
 13. A multiple-plypackaging material comprising:a first layer of permanentlyanti-static/static-dissipative material; a second layer of permanentlyanti-static/static-dissipative material; a third layer of relativelyrigid material having first and second sides, said first and secondlayers being permanently applied to said first and second sides,respectively, of said relatively rigid material so as to sandwich saidrelatively rigid material between said first and second layers, saidfirst and second layers being amine free and having been precast intosolid form and rendered permanently anti-static/static-dissipative priorto application to said first and second sides of said rigid material;and wherein said first and second layers have a surface resistivity ofmore than 10⁵ but less than 10¹² ohms per square.
 14. A multiple-plymaterial as in claim 13 wherein said third layer comprises:a layer ofpaperboard.
 15. A multiple-ply material as in claim 13 or claim 14wherein said permanently anti-static/static-dissipative materialcomprises:an anti-static/static-dissipative plastic material.
 16. Amultiply-ply material as in claim 13 or claim 14 wherein saidpermanently anti-static/static-dissipative material comprises:a plasticfoam material.
 17. A multiple-ply packaging material comprising:a firstlayer of relatively rigid material having first and second surfaces; asecond layer of anti-static/static-dissipative material applied to oneof said first and second surfaces, said second layer being amine-freeand having a surface resistivity of more than 10⁵ but less than 10¹²ohms per square; and said second layer having been applied to said oneof said first and second surfaces while in a solid state, said secondlayer while in said solid state and before application to said one ofsaid first and second surfaces being characterized by the sameamine-free, anti-static/static-dissipative characteristics ascharacterize said second layer after being applied to said one of saidfirst and second surfaces.
 18. The multiple-ply packaging material ofclaim 17 wherein said first layer is paperboard.